A laser annealing apparatus may apply a pulse laser beam on an amorphous silicon film formed on a substrate. The pulse laser beam may be emitted from a laser system such as an excimer laser system. The pulse laser beam may have a wavelength of ultraviolet light region. Such pulse laser beam may reform the amorphous silicon film to a poly-silicon film. The poly-silicon film can be used to form thin film transistors (TFTs). The TFTs may be used in large sized liquid crystal displays.